Reheating metal bodies with recovered blast-furnace energy

摘要

Metal bodies such as billets and blooms are reheated for rolling in a metal-refining operation having a blast furnace by first heating the top gas of the blast furnace to at least 800 DEG C. by means of a plasma torch, then, before the gas has cooled appreciably, burning the heated top gas in a preheating chamber. The metal bodies are exposed in the preheating chamber to the heat of the burning and heated top gas. The heated top gas is mixed with combustion-inducing gas to burn it. Before it is mixed with the heated top gas it is preheated by heat exchange with combustion-product gas withdrawn from the preheating chamber. In this manner it is possible to raise the temperature of this combustion-inducing gas to at least 600 DEG C., so that the burners firing the preheating chamber burn clean. In addition much of the heat of the process is recovered, again reducing energy costs for the system.